Computers are regularly being used for a variety of purposes throughout the world. As computers have become commonplace, computer manufacturers have continuously sought to make them more accessible and user-friendly. One such effort has been the development of natural input methods. For example, speech recognition permits a user to input data into a computer simply by speaking the data out loud. The phonemes of the user speech then are analyzed to convert it into typewritten text Handwriting recognition alternately allows a user to input data by writing on a digitizer with a stylus to create electronic ink. The computer analyzes the shapes of the ink to convert it into typewritten text.
The advent of handwriting input techniques has been particularly beneficial to computer users who employ an East Asian language. Latin languages typically are written with a phonetic character set or alphabet, where each character represents a particular phonetic sound. Even including punctuation, writing in a Latin language requires only a relatively small number of characters. Most, if not all, of the characters used to write in a Latin language thus can be provided on a keyboard. Many East Asian languages, however, are written using a pictographic character set having thousands of characters. Even a large keyboard cannot contain enough keys for a user to write in an East Asian language.
To address this problem, software developers have created specialized programs for converting alphabetic characters into pictographic characters. For example, a computer user in Japan may type a desired word of data using characters from a phonetic alphabet, such as Hiragana or Katakana (collectively referred to herein as “Kana” characters). The user may then activate a Kana-to-Kanji conversion software application, which provides the user with a selection of possible alternates for the word from the Kanji character set. The user can then select the appropriate Kanji character (or characters), which are stored as the input data. While this type of conversion software has allowed East Asian language users to employ computers, it is cumbersome and slow to use.
The new handwriting input techniques have the potential to free East Asian language users from this type of conversion software. Rather than having to tediously convert phonetic characters to a desired pictographic character with a keyboard, the user may now simply write the pictographic character in electronic ink. The computer will then recognize the desired pictographic character from the electronic ink. For example, East Asian language versions of the Microsoft Windows XP Tablet PC operating system provide a special user interface for receiving data from natural input methods. This type of user interface, sometimes referred to as a “TIP” (for text input panel or tablet input panel), includes a handwriting input area. The handwriting area corresponds to an area of a digitizer onto which a user can write with a stylus to createelectronic ink. This electronic ink is then “recognized,” that is, converted to character data.
While these types of natural input techniques can be very convenient for East Asian language users, their usefulness depends upon their recognition accuracy. Some handwriting recognition tools are very accurate for printed East Asian pictographic characters (i.e., where a user lifts the stylus from the digitizer between each stroke making up the pictographic character). It is more difficult, however, for conventional handwriting recognition tools to accurately recognized cursive East Asian pictographic characters (i.e., where a user does not lift the stylus from the digitizer between writing each stroke forming the pictographic character). With cursive writing, a person's individual writing style will have a more pronounced impact on the appearance of a character. Moreover, even a single person may draw different shapes each time that an East Asian pictographic character is written. For example, FIG. 1 illustrates ten cursive samples of the Chinese character 6 (meaning “arrow”) obtained from the same writer. As seen from this figure, it may be difficult for even a human reader to recognize each of these character samples as representations of the same Chinese character for “arrow.”